CNDO/SCF molecular orbital structural studies and charge transfer complex formation between 4,4’-dimethoxydiquinone and uracil

Abstract

Through CNDO/SCF molecular orbital calculations, the structure of 4,4’-dimethoxy- diquinone (DQ) has been discussed and compared with some related compounds. The electron transfer between DQ and uracil was studied in ethanol as an interaction medium. The ionization potentials and the electron affinities of the studied molecules have been calculated in addition to their charge densities giving the columbic potential energy of the donor and acceptor. The experimental charge transfer band lies at 500 nm. The electronic transitions have been calculated for the singlet and triplet transitions in uracil and DQ molecules using the SCF eigenvectors of the two HOMO’s, y_n-1 and y_n, and the two LUMO’s, y_n+1 and y_n+2, using CI theory. The calculated electronic transitions are compared with those of the experimental data to verify the non-planar structure of the DQ molecule.

KEY WORDS: CNDO/SCF molecular orbital calculations, 4,4’-Dimethoxydiquinone, Uracil, Ionization potentials, Electron affinities

Bull. Chem. Soc. Ethiop. 2004, 18(2), 193-204.